Coated pipe and propylene polymer composition therefor

Abstract

The invention relates to a coated pipe comprising a core, an adhesion layer coated on the core and an outer coating layer coated on the adhesion layer, wherein at least the adhesion layer comprises a propylene polymer composition comprising: (A) a propylene homo- or copolymer, and (B) an elastomeric component and to the use of such a propylene polymer composition for coating a pipe.

The invention claimed is: 
     
       1. A coated pipe comprising a core, an adhesion layer, and an outer coating layer, wherein the adhesion layer is intermediate the core and the outer coating layer, wherein the adhesion layer and the outer coating layer comprise a propylene polymer composition comprising:
 (A) a propylene copolymer, and 
 (B) an elastomeric component; 
 wherein the elastomeric component is an elastomeric ethylene copolymer; 
 wherein the coated pipe has an impact resistance at −20° C. of 15 to 40 J/mm according to EN 1411; and 
 wherein the propylene copolymer (A) comprises an ethylene content of about 8% in the outer coating layer and about 11% in the adhesion layer. 
 
     
     
       2. The coated pipe according to  claim 1 , wherein the propylene polymer (A) is a heterophasic propylene copolymer. 
     
     
       3. The coated pipe according to  claim 1 , wherein the elastomeric component (B) is contained in an amount of not more than 30 wt %, based on the weight of the propylene copolymer (A). 
     
     
       4. The coated pipe according to  claim 2 , wherein the heterophasic propylene copolymer comprises:
 (A) a propylene copolymer as a matrix phase; and 
 (B) a rubber component as a dispersed phase. 
 
     
     
       5. The coated pipe according to  claim 1 , wherein the elastomeric component (B) is a hydrocarbon rubber. 
     
     
       6. The coated pipe according to  claim 5 , wherein the hydrocarbon rubber is selected from the group consisting of an ethylene-propylene rubber, an ethylene-propylene-diene rubber, and an ethylene-propylene norbornadiene rubber. 
     
     
       7. The coated pipe according to  claim 1 , wherein the pipe core is made of steel or a fiber reinforced material. 
     
     
       8. The coated pipe according to  claim 1 , wherein a layer of a polar polymer is provided on the core. 
     
     
       9. The coated pipe according to  claim 8 , wherein the layer of the polar polymer is an epoxy layer. 
     
     
       10. The coated pipe according to  claim 1 , wherein the pipe exhibits a peel strength of from 300 to 700 N/cm before hit and from 150 to 450 N/cm after hit according to DIN 30678. 
     
     
       11. The coated pipe according to  claim 1 , wherein the propylene polymer composition exhibits an elongation at break of 50% or more according to ISO 527-2. 
     
     
       12. A method of manufacturing a coated pipe comprising a core, an adhesion layer and an outer coating layer, wherein the adhesion layer is intermediate the core and the outer coating layer, wherein the adhesion layer and the outer coating layer comprise a propylene polymer composition comprising:
 (A) a propylene copolymer, and 
 (B) an elastomeric component 
 wherein the elastomeric component is an elastomeric ethylene copolymer; 
 wherein the coated pipe has an impact resistance at −20° C. of 15 to 40 J/mm according to EN 1411; and 
 wherein the propylene copolymer (A) comprises an ethylene content of about 8% in the outer coating later and about 11% in the adhesion layer. 
 
     
     
       13. The coated pipe according to  claim 1 , wherein the outer coating layer is the outermost coating layer.